package leetcode.leetcode_141;


 class ListNode {
     int val;
     ListNode next;
     ListNode(int x) {
         val = x;
         next = null;
     }
 }

public class Solution {
    public boolean hasCycle(ListNode head) {
        ListNode slow = head ;
        ListNode fast = head ;
        while(fast!=null &&fast.next!=null){
            slow = slow.next;
            fast = fast.next.next;
            if (slow == fast) return true;
        }
        return false;
    }
}